Currently, large OLED lighting luminaires are composed of individual small OLED panels with a typical size around 4×4 inches. These panels are made on a large piece of glass, then packaged and separated from each other by cutting the large glass into smaller pieces with OLEDs disposed thereon. These individual OLED panels can then be sent to a luminaire manufacturer for mechanical and electrical assembly. Because each OLED panel is individually packaged, the assembly is time consuming and requires a wide bezel around the active lighting area.
OLED lighting devices have many advantages as diffuse area light sources. However, there is often a trade-off between the size of the OLED panel and the uniformity of the panel. When the panel size increases, current needs to travel further laterally through the electrode. Since the transparent electrode has limited conductance, the long current path generates resistive loss in the forms of potential drop and resistive heating. The direct result of potential drop is that the panel becomes dimmer in the region further away from the contacts. As a result, currently available OLED panels typically have sizes around 2 to 6 inches.
One way to address this issue is to use buslines to reduce the potential drop, which can increase the size of the panel. However, the use of buslines can significantly increase the cost of the panel. In addition, for each different size, the panel and/or busline needs to be re-designed along with the tooling and masks used in the fabrication process. Further, even with the application of buslines, the increase in panel size is limited.
Thus, there is a continuing need in the art for an OLED lighting device that can be made in any size without the need for redesigning the equipment used in the fabrication process each time the size of the lighting device is changed. The present invention addresses this need in the art.